1. Field of the Invention
The present invention relates in general to a method of joining together optical fibers and in particular to a method of joining or splicing fused silica fibers having a relatively high softening temperature by utilizing a CO.sub.2 -laser.
2. Description of the Prior Art
In recent years, studies on the optical fibers have made a rapid and noticeable progress to such a practical level that the optical fiber can be realized with a low loss in the order of several dB's per kilometer. Communication systems utilizing the optical fiber have entered upon the stage of practical application. Under the circumstances, the optical fiber splicing technique provides a problem which attracts increasingly attention of those skilled in the art. The optical fiber splicing technique may in general be classified into two varieties, one of which resides in forming a releasable joint, while the other method is directed to the formation of a permanent joint. In the case of the latter method, the optical fibers to be joined are aligned so as to directly abut on each other at the end faces thereof by using a sleeve or like means. As an alternative, the optical fibers are joined through fusion or bonded through an appropriate adhesive agent. The method of fusing together the optical fibers has an advantage that the reflexion loss at the formed joint can be reduced as compared with the directly abutting method and besides is advantageous over the bonding method in that the joint having a greater strength can be accomplished. For these reasons, the fusing method is regarded as one of the most effective means for forming the permanent joint of the optical fibers.
In the first attempt for joining together the optical fibers through the fusing method as developed by D. L. Bisbee, the fused joint between the optical fibers having a relatively low softening temperature or point (about 630.degree. C.) has been done by means of a heated nichrome wire. However, this method cannot be applied to the joining or splicing of fused silica or fused quartz fibers of a high softening point which are now employed in most practical applications.